The goal of the research described in this proposal is to identify and characterized modifications on peptides and proteins of high molecular weight (5,000-50,000 amu) by mass spectrometry. This will be done by a combined approach of classical protein chemistry and mass spectrometry on a Bio-Ion time-of-flight mass spectrometer with 252Cf ionization source. This grant is for the purchase of the mass spectrometer and the accessories required for putting it into operation. This facility will be a new resource in the area, and a user group at Cold Spring Harbor Laboratory has been found to take advantage of this new instrumentation. The projects described in the proposal all involve the analysis of modifications on biologically active peptides and proteins including: 1) growth and differentiation factors, 2) synthetic peptides, 3) proteins on two dimensional gel electrophoresis, 4) cAMP dependent protein kinases, 5) cellular oncogene products, 6) nuclear oncogene products, 7) phospholipase A2, 8) heat shock proteins, and 9) yeast protein kinases. The Bio-Ion time-of-flight mass spectrometer is the only instrument commercially available that has the demonstrated ability to measure the mass of proteins in excess of 24,000 amu, with 0.01% resolution, at 10-50 pmol of protein. Mass spectrometric analysis of proteins will be performed as part of a multidisciplinary approach to understanding the structure and function of proteins with important physiological roles.